1. Technical Field
The present invention relates to optical imaging devices and, particularly, to an optical lens group and a lens module.
2. Description of Related Art
Currently, along with the development of electronic devices having multiple functions, image pick-up apparatuses have become widely used in a variety of consumer electronic devices, such as notebook computers, personal digital assistants (PDAs), cellular telephones, etc. In the meantime, demand for improving image quality is increasing, which essentially depends on the quality of a lens module of the image pick-up apparatus. That is, a lens module with high image quality is desired.
Referring to FIG. 4, an optical lens group 20 includes two lenses 24, 26. The lens 24 and lens 26 each has a central portion and a peripheral portion. The peripheral portion of the lens 24 includes a protuberance 242, and the peripheral portion of the lens 26 includes a protuberance 262 coupled with the protuberance 242. The protuberance 242 has a surface 244 and the protuberance 262 has a surface 264. The two surfaces 244, 264 are both incline planes and have the same gradient. When assembling the two lenses 24 and 26, the surfaces 244 and 264 contact each other to fix the lens 24 with the lens 26. However, this combination requires the surfaces 244 and 264 to be manufactured very precisely. Furthermore, the friction force between the surface 244 and the surface 264 may cause the deformation of the two lenses 24, 26. The larger the contact area between the surface 244 and the surface 264 is, the larger the friction force between the two lenses 24, 26 is. Due to the friction force, the lens 24 may be inclined relative to the lens 26 after the lens 24 coupled to the lens 26. Therefore, the optical axis of the lenses 24 and 26 may be not aligned to each other. Thus, images generated by a lens module having the above optical lens group 20 may be distorted, for example change in shape or fuzziness.
Therefore, a new optical lens group is desired to overcome the above mentioned problems.